System and methods for positioning bone cut guide

ABSTRACT

Systems and methods for positioning a cut guide using navigation-based techniques are discussed. For example, a system for use in an orthopedic surgery on a target bone can comprise a cut guide adjustably positionable onto the target bone via two or more coupling receptacles created on the target bone. The coupling receptacles can include one or more guide members and a plurality of landing members. The system also includes an input interface that can receive a target bone representation, and a model receiver module that can receive a generic post-coupling bone model. The target bone representation can include a data set representing two or more landing sites of the target bone, and the generic post-coupling bone model can include a data set representing a bone having two or more coupling receptacles each sized, shaped or otherwise configured to receive and secure the respective coupling feature of the landing members. The system can include a navigation-based guide coupling preparation system that can generate a plan for positioning the cut guide onto or conforming to the target bone. The system can further include a display module that provides presentations of the coupling between the target bone and the cut guide.

CLAIM OF PRIORITY

This patent application is a continuation of U.S. patent applicationSer. No. 16/016,527, titled “System and Methods for Positioning Bone CutGuide,” filed on Jun. 22, 2018, which is a divisional of U.S. patentapplication Ser. No. 14/634,363, titled “System and Methods forPositioning Bone Cut Guide,” filed on Feb. 27, 2015, which is herebyincorporated by reference in its entirety and which claims the benefitof priority of U.S. Provisional Patent Application No. 61/946,428,titled “System and Methods for Positioning Bone Cut Guide,” filed onFeb. 28, 2014, which is hereby incorporated by reference herein in itsentirety.

TECHNICAL FIELD

This document relates generally to computer-aided orthopedic surgery,and more specifically to systems and methods for positioning a cut guideto a target bone and for altering the target bone using the cut guide.

BACKGROUND

The use of computers, robotics, and imaging to aid orthopedic surgery iswell known in the art. There has been a great deal of study anddevelopment of computer-aided navigation and robotics systems used toguide surgical procedures. For example, a precision freehand sculptor(PFS) employs a robotic surgery system to assist the surgeon inaccurately cutting a bone into a desired shape. In interventions such astotal hip replacement, computer-aided surgery techniques have been usedto improve the accuracy, reliability of the surgery. Orthopedic surgeryguided by images has also been found useful in preplanning and guidingthe correct anatomical position of displaced bone fragments infractures, allowing a good fixation by osteosynthesis.

A cut guide can be used in an orthopedic surgery to assist a surgeon incutting or modifying some portions of a target bone. For example, injoint replacement surgeries such as total hip replacement (THR) or totalknee replacement (TKR), a cut guide can be temporarily attached to thetarget bone such as a femur or a tibia. An orthopedic surgical cuttingtool can be used together with the cut guide to allow the surgeon toselectively cut portions of the ends of the target bone and replacedwith endoprosthetic implants. Positioning a cut guide for use inpreparing the target bone can be a time consuming and complicatedprocess, which is critical to positive outcomes for the patient.

SUMMARY

Quick and reliable positioning of a cut guide can be crucial to theoutcome of orthopedic surgeries such as prosthesis implantation. Injoint replacement surgeries, for example, portions of the articulationtissues of a target bone, such as acetabulum, a femur, or a tibia, needto resected and altered to allow an implant to be securely positionedonto the target bone. A cut guide positioned on the target bone can beused to guide a cutting saw to resect the target bone to a desiredshape. Proper positioning of the cut guide on the bone can improve theaccuracy of the bone resection and reduce procedure time. On thecontrary, improper positioning of the cut guide can result inundesirable cutting surfaces on the target bone, which can further causeimpingement, increased rates of implant dislocation, wear and failure ofthe implant, among many other complications. The procedure time can alsobe lengthened due to the requirement of modifying the undesirablecutting shape.

Positioning of cut guide onto a target bone usually requires a surgeonto mentally map and compare the shape, orientation, and relativepositions of the implant and the target bones. Mechanical jigs thatalign to general specifications, rather than aligning to parametersoptimal for the patient. This method can be difficult to operate and maysuffer from lack of reliability and certainty. Determining andvisualizing the correct positions and orientations of the prosthesiswith respect to the target bone can be practically difficult.Computer-aided tools can be used to assist the surgeon in positioningthe cut guide relative to the bone. However, often thecomputer-assistance is limited to intraoperative navigation oftraditional cutting jigs. The designs of these jigs, the tools to alignthem, and the implants that they support are all compromises meant toserve a general population. Other systems uses computers to analyzepatient specific images used to design patient-conforminginstrumentation and sometimes even implants specific to the patient.However, these images either use ionizing radiation (e.g. computedtomography images) or are prone to error or gaps in tissuedifferentiation (e.g. magnetic resonance imaging). Therefore, thepresent inventors have recognized that there remains a considerable needfor systems and methods that can assist the surgeon in reliablypositioning a cut guide onto the target bone with improved accuracy,speed, and consistency, while still allowing for some customization.

Various embodiments described herein can help improve the efficacy andthe reliability in positioning a cut guide onto a target bone to alter aportion of the target bone. For example, an orthopedic surgical devicecan comprise a cut guide that is configured to be adjustably positionedonto or otherwise conform to the target bone. The cut guide includes aplurality of landing members. Each landing member includes a couplingfeature that can removably couple to a landing site of the target bone.The cut guide also includes one or more guide members on the guide body.Each guide member can be sized, shaped or configured to constrain andguide a cutting tool along a respective cutting trajectory. The guidemember can guide the cutting tool to cut the target bone along therespective cutting trajectory when the landing members are coupled tothe landing site of the target bone. In an example, the guide member caninclude guide slots or surfaces for guiding a surgical saw in makingcuts on a target bone. Multiple cut guides with the same cuttingtrajectories can be made available that have different landing memberplacements, in order to accommodate different sizes and shapes of bones.

A system embodiment for use in an orthopedic surgery on a target bonecan comprise a cut guide adjustably positionable onto a target bone viatwo or more coupling receptacles created on the target bone. The cutguide can include one or more guide members and a plurality of landingmembers. The system also includes an input interface that can receive atarget bone representation, and a model receiver module that can receivea generic post-coupling bone model. The target bone representation caninclude a data set representing two or more landing sites of the targetbone, and the generic post-coupling bone model can include a data setrepresenting a bone having two or more coupling receptacles each sized,shaped or otherwise configured to receive and secure the respectivecoupling feature of the landing members. The system can include anavigation-based guide coupling preparation system that can generate aplan for positioning the cut guide onto or conforming to the targetbone. The system can further include a display module that providespresentations of the coupling between the target bone and the cut guide.

A method embodiment for operating a system for use in an orthopedicsurgery on a bone can comprise the operations of providing a cut guidethat is adjustably positionable onto or conformed to the target bone,and receiving a target bone representation and a generic post-couplingbone model. The target bone representation can include a data setrepresenting two or more landing sites of the target bone, and thegeneric post-coupling bone model can include a data set representing abone having two or more coupling receptacles configured to receive andsecure the respective coupling feature of the landing members. Themethod can comprise the operations of generating a cut guide positioningplan for positioning the cut guide onto or conforming to the targetbone, producing at the landing sites coupling receptacles that aresized, shaped or configured to receive and secure the respectivecoupling features of the landing members, and attaching the cut guide tothe landing site of the target bone by engaging the coupling featureswith the coupling receptacles.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects of the invention will be apparent to persons skilled in the artupon reading and understanding the following detailed description andviewing the drawings that form a part thereof, each of which are not tobe taken in a limiting sense. The scope of the present invention isdefined by the appended claims and their legal equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are illustrated by way of example in the figures ofthe accompanying drawings. Such embodiments are demonstrative and notintended to be exhaustive or exclusive embodiments of the presentsubject matter.

FIGS. 1A-D illustrate an example of an orthopedic surgical device foruse in operating on a target bone.

FIGS. 2A-B are block diagrams that illustrate an example of a cut guidepositioning system.

FIGS. 3A-B illustrate an example of preparing coupling receptacles on atarget bone.

FIGS. 4A-B are block diagrams that illustrate an example of anorthopedic surgical system.

FIGS. 5A-C illustrate an example of selecting a set of guide members andgenerating an ordered sequence of bone cuts on a target bone.

FIG. 6 is a flowchart that illustrates an example of a method forpositioning a cut guide onto a target bone.

FIG. 7 is a flowchart that illustrates an example of a method forproducing coupling receptacles on the target bone.

FIG. 8 is a flowchart that illustrates an example of a method forresecting a portion of a target bone using a cut guide.

FIG. 9 is a block diagram that illustrates an example of a computersystem within which instructions for causing the computer system toperform bone cut positioning may be executed.

DETAILED DESCRIPTION

Disclosed herein are systems, devices and methods for positioning a cutguide onto a target bone using a plurality of coupling receptaclesproduced with the assistance of a navigation-based guide couplingpreparation system. Various embodiments described herein can helpimprove the efficacy and the reliability in osteoplasty planning, suchas resecting portions of bone surface for cut guide positioning. Themethods and devices described herein can also be applicable to planningsurgery of pathological bones under various other conditions.

FIGS. 1A-D illustrate an example of an orthopedic surgical device foruse in operating on a target bone 300. The orthopedic surgical devicecomprises a cut guide 100, illustrated in FIG. 1B, configured to beadjustably positioned onto or otherwise conform to the target bone 300as illustrated in FIG. 1A. The cut guide 100 includes a guide body 110forming the cut guide 100, and a plurality of landing members such as130A-B. The guide body 110 forms the supporting structure of the cutguide 100, and can be made of metal, alloy, polymer, or other rigiddimensionally stable materials.

The guide body 110 includes one or more guide members 120A-D. Each guidemember can be sized, shaped or otherwise configured to constrain andguide a cutting tool (not shown) along a respective cutting trajectorydetermined by the guide member. The guide members 120A-D can haveslotted structures sized to securely receive and constrain the cuttingtool, and allow the cutting tool to move freely within the respectiveslotted structure. The guide members 120A-D can have openings on anexterior of the guide body 110. The openings can be sized to facilitateplacement of the cutting tool into one or more of the guide members120A-D, and connection between a portion of the cutting tool and anexternal driving device such as a robotic arm for manipulating thecutting tool within the guide members.

Each guide member (such as a slot) has a pre-determined orientation thatdefines the cutting trajectory. As illustrated in FIG. 1B, the guidemember 120A is horizontally oriented, the guide member 120B verticallyoriented, and the guide members 120C and 120D each oriented at specifiedtilt angles. The orientations of the guide members 120A-D can bedifferent from each other, thereby allowing bone cuts from differentangles. In some examples, at least two guide members have the sameorientation. This provides a system end-user with flexibility inselecting desired amount of bone cut along a particular cutting plane.The number of guide members on the guide body 110 can be more than whatis needed for resecting a particular target bone. Such redundancy ofguide members can make the cut guide 100 a generic tool for modifyingtarget bones that have different desired post-operative sizes or shapes.

Each of the landing members 130A-B on the cut guide 100 can include arespective coupling feature. The coupling features can be configured toremovably couple to the target bone 300 at two or more landing sites onthe target bone 300. The landing sites define desired locations on thetarget bone onto which the cut guide can be securely positioned.

As illustrated in FIG. 1B, on the cut guide 100, the coupling featurescan further include protruding portions such as 131A-B extended from thelanding members 130A-B. The protruding portions 131A-B can have a shapeof a cylinder, a cube, a rectangular prism, a triangular prism, apyramid, a cone, or other three-dimensional structures. As illustratedin FIG. 1A, on the target bone 300, two or more coupling receptaclessuch as 331A-B can be produced at the landing sites with assistance of anavigation-based guide coupling preparation system. The couplingreceptacles 331A-B on the target bone 300 each include a recessedportion that is sized, shaped or otherwise configured to receive andsecure a respective protruding portion, such as 131A-B, of the couplingfeatures on the cutting guide 100. For example, when the protrudingportion 131A is in a shape of rectangular prism, the correspondingcoupling receptacle 331A can be a receptacle in a shape of rectangularprism sized to securely match the protruding portion 131A. Theinterfacing surfaces of the protruding portion 131A and of the couplingreceptacle 331A can be processed to allow for an interference fit in atleast one dimension, such that the protruding portion 131A can be heldwithin the coupling receptacle 331A by compression or by friction. Theamount of interference can be produced at either or both of theinterfacing surfaces of the protruding portion 131A and of the couplingreceptacle 331A so as to achieve desired tightness of fit.

In some examples, the size and shape of the coupling receptacle can alsobe determined using the information including the location of thelanding site of the target bone, and the anatomical, mechanical, orphysical properties of the bone and surrounding tissues at the landingsite. The coupling between the cut guide 100 and the target bone 300 cantherefore be accomplished by engaging the protruding portions 131A-Binto the respective coupling receptacles 331A-B on the target bone 300.Examples of creating the coupling receptacles 331A-B for positioning thecut guide 100 onto the target bone 300 are discussed below, such as withreference of FIG. 3.

The landing members 131A-B can be an extended portion of the guide body100. In some examples, the landing members 131A-B can be structuresseparate from but fixed onto an exterior of the guide body 100. In anembodiment, at least one of the landing members is reconfigurable. Thereconfigurable landing member can be connected to the guide body 100 viaan adjustable connector, through which the reconfigurable landing membercan have at least one degree of freedom of movement relative to theguide body 100. Examples of the adjustable connector can include areleasable lock, such that the reconfigurable landing member can beadjustably locked onto the guide body 110 when the reconfigurablelanding member is positioned once the cutting guide is at the landingsite and attached to the target bone, or when the reconfigurable landingmember is not used for attaching to the target bone.

FIG. 1C illustrates an example of positioning the cut guide 100 onto thetarget bone 300 such as via coupling between the protruding portion131A-B and the coupling receptacles 331A-B. The guide members 120A-D canguide a cutting tool (not shown) to cut the target bone 300 along thecutting trajectories 150A-D as defined by the orientations of the guidemembers 120A-D. In some examples, the protruding portions 131A-B of thelanding members do not cross the cutting trajectories or the cuttingplanes 150A-D. This will prevent bone cutting along the cuttingtrajectories from interfering with the protruding portion 131A-B thatare coupled to the coupling receptacles 331A-B. When the bone cut iscompleted, an implant 500 can be attached to the post-operative bone. Asillustrated in FIG. 1D, the implant 500 can include an interfacingsurface sized and shaped to be in close contact with the post-operativesurfaces of the target bone. The interfacing surface can includemultiple facets 550A-D oriented in conformity with the cutting planes150A-D, respectively.

FIGS. 2A-B are block diagrams that illustrate an example of a cut guidepositioning system 200 for use in an orthopedic surgery. The system 200includes a cut guide 100, a model receiver module 210, an inputinterface 220, a navigation-based guide coupling preparation system 230,and a communication interface 240. The system 200 can be configured tosecurely position the cut guide 100 onto a target bone via two or morecoupling receptacles created on the target bone. Once positioned on thetarget bone, the cut guide 100 can be used to guide resection of aportion of the target bone for prosthesis implantation.

The model receiver module 210 can be configured to receive a genericpost-coupling bone model (M_(coupling)). The model M_(coupling) caninclude a data set representing a bone having an anatomical origincomparable to the target bone to be altered by the system 200. The dataset can include shape or appearance information of the bone. The modelM_(coupling) can be in a form of a parametric model, a statisticalmodel, a shape-based model such as a statistical shape model, or avolumetric model. The model M_(coupling) can also be based on physicalproperties of the normal bone, such as an elastic model, a geometricspine model, or a finite element model.

The model M_(coupling) can include representations of two or morecoupling receptacles each sized, shaped or otherwise configured toreceive and secure the respective coupling feature on the cut guide 100,such as protruding portions 131A-B. The coupling receptaclerepresentation can include indications of locations, sizes, shapes,volume, or other geometric or morphological descriptors. In an example,the model M_(coupling) can be derived from a plurality of images ofpost-coupling bones (i.e., bones with the coupling receptacles created)having comparable anatomical origin from a group of subjects. In anotherexample, the coupling receptacle representation includescomputer-simulated graphs or annotative markings that identify theboundaries of the recessed portions of the coupling receptacle. Thesizes, shapes, volume, or other geometric or morphological descriptorsof the coupling receptacle representations can be determined using thesize, shape, volume, or other geometric or morphological descriptors ofthe respective protruding portion (such as 131A-B) of the landingmembers on the cut guide 100. The computer-simulated coupling receptaclerepresentation can be separately generated and then added to acoupler-free normal bone model to create the generic post-coupling bonemodel M_(coupling).

The model M_(coupling) can be generated using a system external to thesystem 200, and stored in a machine-readable medium such as a memorydevice. The model receiver module 210 can retrieve model M_(coupling)from the memory device upon receiving a command from an end-user.Alternatively, the system 200 can include a post-coupling bone modelgenerator that can create a generic post-coupling bone model(M_(coupling)) using shape data or appearance data. The shape data mayinclude geometric characteristics of a bone such as landmarks, surfaces,boundaries of three-dimensional images objections. The appearance datamay include both geometric characteristics and intensity information ofa bone. The shape or appearance data can be constructed from a pluralityof medical images of the normal bones of comparable anatomical originfrom a group of subjects. The medical images can include two-dimensional(2D) or three-dimensional (3D) images, including an X-ray, an ultrasoundimage, a computed tomography (CT) scan, a magnetic resonance (MR) image,a positron emission tomography (PET) image, or a single-photon emissioncomputed tomography (SPECT) image, or an arthrogram. The shape orappearance data can be constructed from a plurality of point cloudsacquired from bones having comparable anatomical origin from a group ofsubjects using a coordinated measuring system such as one or moretracking probes.

The input interface 220 can be configured to receive a target bonerepresentation (X_(pre-coupling)) from a patient database.Alternatively, the target bone representation (X_(pre-coupling)) can begenerated by an imaging system or other image acquisition module withinor external to the system 200, and received by the system 200 via theinput interface 220. Examples of target bone can include an acetabulum,a proximal or distal extremity of a femur, a proximal or distalextremity of a tibia, or other bones in a body. The representationX_(pre-coupling) can be in a form of a medical image, a point cloud, aparametric model, or other morphological description of the target bone.The representation X_(pre-coupling) includes a data set representing theshape, appearance, or other morphological characteristics of the targetbone. The representation X_(pre-coupling) includes two or more landingsite representations on a surface of the target bone where two or morecoupling receptacles can be created.

The navigation-based guide coupling preparation system 230 can include acut guide positioning planning module 231 configured to generate a planfor positioning the cut guide onto or conforming to the target bone. Thecut guide positioning planning module 231 can include a registrationmodule 232 and a positioning plan formation module 233.

The registration module 232 can take as an input the genericpost-coupling bone model M_(coupling) and the target bone representationX_(pre-coupling), register M_(coupling) to X_(pre-coupling), and createa registered post-coupling bone model M_(coupling). FIG. 2B is a blockdiagram illustrating an embodiment of the registration module 232. Inthis embodiment, the registration module 232 can include a segmentationmodule 271, a model transformation module 272, a matching module 273,and an alignment module 274. The segmentation module 271 can beconfigured to partition the model M_(coupling) and the target bonerepresentation X_(pre-coupling) each into a plurality of segments. Eachsegment can represent a specified anatomical structure. In someexamples, a label can be assigned to each of the segments, such that thesegments with the same label share specified characteristics such as ashape, anatomical structure, or intensity. For example, the segmentationmodule 271 can differentiate a portion of M_(coupling) containing thecoupling receptacle representation from a different portion of theM_(coupling) free of coupling receptacle representation, and identifyfrom the segments of the M_(coupling) a registration area free ofcoupling receptacles.

The model transformation module 272 can transform the genericpost-coupling bone model M_(coupling) to create the registeredpost-coupling model M_(coupling) using a comparison between thecoupler-free segment of M_(coupling) and the corresponding segments ofthe X_(pre-coupling). The transformation can include linear or nonlinearoperations such as scaling, rotation, translation, expansion, dilation,or other affine transformation. The transformation can include rigidtransformations that preserve the distance (such as translation,rotation, and reflection) or non-rigid transformations such asstretching, shrinking, or model-based transformations such as radialbasis functions, splines, or finite element model. In some embodiments,the registration module 232 can employ both the rigid transformation tobring the M_(coupling) in global alignment with the size and orientationof the target bone representation X_(pre-coupling), and the non-rigidtransformation to reduce the local geometric discrepancies by aligningthe M_(coupling) with the X_(pre-coupling). In some embodiments, themodel transformation module 272 can determine a desired transformation Θthat minimizes the difference between the identified coupler-freesegments on the M_(coupling) and the corresponding segments ofX_(pre-coupling). The desired transformation Θ_(opt) can then be appliedto the M_(coupling) to create the registered post-coupling modelM_(coupling)=Θ_(opt)(M_(coupling)). The model M_(coupling) containsdesired size, shape, volume, and other geometric or morphologicaldescriptors of the coupling receptacles on the target bone.

The matching module 273 can match one or more segments of the registeredpost-coupling model M*_(coupling) to the corresponding registration areaof the X_(pre-coupling). The alignment module 274 can align theremaining segments of M_(coupling) with the remaining segments of thetarget bone representation X_(pre-coupling) based at least on thematching. This produces an alignment between the registeredpost-coupling model M_(coupling) and the target bone representationX_(pre-coupling).

Referring back to FIG. 2A, the positioning plan formation module 233 canuse the comparison between the registered post-coupling modelM*_(coupling) and the target bone representation X_(pre-coupling) todetermine the two or more landing sites on the target bone forrespectively creating the coupling receptacles, and determining sizes,shapes, volume, or other geometric or morphological descriptors of thecoupling receptacles. The comparison can be performed on all or selectedsegments (such as the segments containing the coupling receptacles) ofthe registered post-coupling model M_(coupling) and the target bonerepresentation X_(pre-coupling).

As illustrated in FIG. 2A, the system 230 can further include a couplingreceptacle preparation tool 235. The coupling receptacle preparationtool 235 can be a temporary tool used for producing the two or morecoupling receptacles on the landing site of the target bone according tothe positioning plan generated by the positioning plan formation module233. The coupling receptacle preparation tool 235 can be operatedmanually by an end-user, or automatically by a computer-controlledsystem. An example of such a cutting tool can be found in Brisson etal., U.S. Pat. No. 6,757,582, entitled “Methods and systems to control ashaping tool”, which is incorporated herein by reference in itsentirety. Examples of the coupling receptacle preparation tool and thecreation of the coupling receptacles are discussed below, such as withreference of FIG. 3.

In some examples, the coupling receptacle preparation tool 235 isoperated to progressively create the coupling receptacles using acomparison between the registered post-coupling model M*_(coupling) anda perioperative target bone representation X_(peri-coupling). The inputinterface 220 can receive the perioperative target bone representationX_(peri-coupling) including coupling receptacle representations duringthe process of creating the coupling receptacles. The perioperativerepresentation X_(peri-coupling) can be updated in real-time such asusing a camera and a monitoring device, or upon receiving a usercommand. The cut guide positioning planning module 231 can compute asimilarity metric between the desired coupling receptacles on theregistered post-coupling model M*_(coupling) and the correspondingperioperative coupling receptacles on the perioperative target bonerepresentation X_(peri-coupling). Examples of the similarity metric caninclude L1 norm, L2 norm (Euclidian distance), infinite norm, or othernorm in the normed vector space. The similarity metric can also includecorrelation coefficient, mutual information, or ratio image uniformity.If the similarity metric meets a specified criterion such as fallingwithin a specified range or below a threshold value, the perioperativecoupling receptacles on the representation X_(peri-coupling) are deemedsubstantially similar to the desired coupling receptacle on theregistered post-coupling model M*_(coupling), and the positioning planformation module 233 can generate an indicator indicating the completionof the coupling receptacle preparation.

The communication interface 240, coupled to the navigation-based guidecoupling preparation system 230, can be configured to presentinformation of the model and the target bone in audio, visual, or othermulti-media formats to assist the surgeon during the process of creatingand evaluating a surgical plan. The information presented can includethe generic post-coupling bone model M_(coupling), the registeredpost-coupling model M*_(coupling), the target bone representationX_(pre-coupling), the landing sites representation and the couplingreceptacles on the target bone, the perioperative target bonerepresentation X_(peri-coupling), the similarity metric between thedesired coupling receptacles and the perioperative coupling receptacles,and the indication of the completion of the coupling receptaclepreparation. In an example, the communication interface 240 can includea display module such as a monitor for displaying dialog, text, 2D or 3Dgraphs, or animations of the bone models and the target bonerepresentation, among other things. The graphs or animation can includecolor-codes, annotations, or other visual enhancements on theperioperative coupling receptacles. The communication interface 240 canalso include a user input device configured to receive user input toaccept or modify the surgical plan generated by the surgical planningmodule 130.

The communication interface 240 can communicate over an internal bus toother modules within the system 200. In some examples, the communicationinterface 240 can be configured to communicate with one or more externaldevices including, for example, a tracking device, a positioning device,a surgical navigation system, or a medical robotic system. Thecommunication interface 240 can include both wired interface (such ascables coupled to the communication ports on the communication interface240) and wireless connections such as Ethernet, IEEE 802.11 wireless, orBluetooth, among others.

FIGS. 3A-B illustrate an example of preparing coupling receptacles on atarget bone 300. In this example, two coupling receptacles 331A-B arecreated at two different landing sites 330A-B on the surface of thetarget bone 300. The coupling receptacles can be created using atemporary coupling receptacle preparation tool 335, or any suitablesurgical cutting tool, according to a positioning plan such as generatedby the cut guide positioning planning module 231. The couplingreceptacles 331A-B can each include a respective recessed portion sized,shaped or otherwise configured to receive and secure a protrudingportion of the coupling feature on the landing members of a cut guide100, such as the protruding portions 131A-B. The landing sites 330A-B,as well as the sizes, shapes, volume, or other geometric ormorphological descriptors of the coupling receptacles, can be determinedby the cut guide positioning planning module 231. In an example, thesize and shape of the coupling receptacles can be determined based onthe size and shape of the protruding portions 131A-B of the landingmembers. The recessed portion of the coupling receptacles 331A-B can bein a shape of a cylinder, a cube, a rectangular prism, a triangularprism, a pyramid, a cone, or other three-dimensional shapes. The sizeand shape of the coupling receptacles can also be determined based onthe location of the landing sites, or based on the anatomical,mechanical, and physical properties of the bone and soft tissues at thelanding sites.

The temporary coupling receptacle preparation tool 335 can be anembodiment of the coupling receptacle preparation tool 235. In anexample where the coupling receptacles include recessed portions such as331A-B for receiving and securing the protruding portions of the landingmembers, the coupling receptacle preparation tool 335 can include asurgical drill, a surgical mill, a surgical saw, or other surgicalequipment capable of creating the recessed portion on the target bone.The temporary coupling receptacle preparation tool 335 can be operatedmanually by an operator such as a surgeon. Alternatively, it can beconnected to and operated by an automated computer-controlled systemsuch as a precision freehand sculptor (PFS) or other robotic surgicalsystem.

FIGS. 4A-B are block diagrams that illustrate an example of anorthopedic surgical system 400 for operating on a target bone. Thesystem 400 includes a cut guide 100, a model receiver module 410, aninput interface 420, a navigation-based guide coupling preparationsystem 230, a navigation-based surgical system 450, and a communicationinterface 440. The system 400 includes some or all components of thesystem 200, and thus can be configured to position the cut guide 100onto a target bone via two or more coupling receptacles created on thetarget bone. Additionally, the system 400 can be configured to assist inbone cut after the cut guide is positioned onto or otherwise conforms tothe target bone.

The model receiver module 410 can be an embodiment of the model receiver210, and can receive a generic post-coupling bone model (M_(coupling)).Additionally, the model receiver module 410 can be further configured toreceive a generic post-operative bone model (M_(post-op)) including adata set representing a shape or appearance of a post-operative bone(i.e., after the bone cut). The model M_(post-op) can be in a form of aparametric model, a statistical model, a shape-based model such as astatistical shape model, or a volumetric model. The model M_(post-op)can be derived from a plurality of images of post-operative bones havingcomparable anatomical origin from a group of subjects. Alternatively, atleast a portion of the model M_(post-op), such as resected surfaces thatinterface with the implant 500, can be computer-simulated representationof the post-operative bone surface. The post-operative bone modelM_(post-op) can be generated using an external system and retrieved froma database, or it can be generated by a system within or external to thesystem 400.

The input interface 420 can be an embodiment of the input interface 220,and can receive a target bone representation (X_(pre-coupling))including a data set representing the shape, appearance, or othermorphological characteristics of the target bone includingrepresentations of the two or more landing sites on the target bone.Additionally, the input interface 420 can be further configured toreceive a preoperative target bone representation including a data setrepresenting a portion of the target bone to be altered (X_(pre-op)),which can be different and broader than the landing sites on the targetbone. A set of bone cuts on the target bone can be determined by thenavigation-based surgical system 450. The representation X_(pre-op) caninclude one of more of a medical image, a point cloud, a parametricmodel, or other morphological description of the target bone. In someexamples, the input interface 420 can be configured to be coupled to animaging system or other image acquisition module within or external tothe system 400. The post-operative bone model M_(post-op) can have dataformat or modality comparable to the target bone representationX_(pre-op).

In some embodiments, the representation X_(pre-op) can be taken as thepost-coupling representation of the target bone, that is, the targetbone presentation X_(pre-coupling) with two or more coupling receptaclescreated according to the navigation-based guide coupling preparationsystem 230. The representation X_(pre-op) thus includes both a data setrepresenting a portion of the target bone to be altered as well as thecoupling receptacle representations.

The navigation-based surgical system 450 can include a surgical planningmodule 451 configured to generate a surgical plan for altering at leasta portion of the target bone when the cut guide is securely positionedonto or otherwise conforms to the target bone. Similar to the cut guidepositioning planning module 231, the surgical planning module 451 caninclude a registration module 452 and a surgical plan formation module453.

The registration module 452 can be configured to register M_(post-op) toX_(pre-op) and create a registered post-operative bone modelM_(post-op). FIG. 4B is a block diagram illustrating an embodiment ofthe registration module 452. Similar to the registration module 232 inFIG. 2B, the registration module 452 in this embodiment includes asegmentation module 471, a model transformation module 472, a matchingmodule 473, and an alignment module 474. The segmentation module 471 canpartition the bone model M_(post-op) and the pre-operative bonerepresentation X_(pre-op) each into a plurality of segments. Eachsegment can represent a specified anatomical structure. In someexamples, a label can be assigned to each of the segments, such that thesegments with the same label share specified characteristics such as ashape, anatomical structure, or intensity. For example, the segmentationmodule 471 can differentiate a portion of the M_(post-op) containing theresection surface representation from a different portion of theM_(post-op) free of resection surface representation, and identify fromthe segments of the M_(post-op) a registration area free of resectionsurface representation.

The model transformation module 472 can transform the genericpost-coupling bone model M_(post-op) to create a registeredpost-operative bone model M*_(post-op), such as using a comparisonbetween the segment of the M_(post-op) free of resection surfacerepresentation and the corresponding segments of the X_(pre-op). Thetransformation can include linear or nonlinear operations, rigid ornon-rigid transformations as discussed with reference to FIG. 2B. Themodel transformation module 472 can determine a desired transformation Ψthat minimizes the difference between the identified couplingreceptacle-free segments on the M_(post-op) and the correspondingsegments of X_(pre-op). The desired transformation Ψ_(opt) can then beapplied to the M_(post-op) to create the registered post-operative modelM_(post-op)=Ψ_(opt)(M_(post-op)). The model M*_(post-op) containsdesired size, shape, volume, and other geometric or morphologicaldescriptors of the bone cuts on the target bone.

The matching module 473 can match one or more segments of the registeredpost-operative model M*_(post-op) to the corresponding registration areaof the X_(pre-op), and align the remaining segments of M*_(post-op) withthe remaining segments X_(pre-op) based at least in part on thematching. This produces an alignment between the registeredpost-operative model M*_(post-op) and the target bone representationX_(pre-op).

The surgical plan formation module 453 can be configured, using theregistered post-operative model M*_(post-op), to generate a surgicalplan for cutting the target bone such that the altered target bone is insubstantial conformity to the registered post-operative modelM*_(post-op). The surgical plan formation module 453 can include a guidemember selection module to select one or more guide members from thoseavailable (such as 102A-D) on the cut guide 100. In an embodiment, theguide member selection module can compare the orientations of thedesired bone cuts as defined by the registered post-operative modelM_(post-op) to the cutting trajectories of the available guide membersin the cut guide 100, and select the guide members that match theorientation of the desired bone cuts.

The surgical plan formation module 453 can also include a cuttingsequence scheduler module to determine an ordered sequence of executingbone cuts along the cutting trajectories (such as 150A-D) associatedwith the selected guide members. The cutting sequence can be determinedusing the anatomical, geometric, physical and mechanical properties ofthe portions of the bone to be altered. The cutting sequence can also bescheduled considering the locations, sizes, shapes, volumes, or othergeometric or morphological descriptors of the coupling receptaclesrelative to the cutting trajectories. For example, the bone cuts alongthe cutting trajectories that are spatially farther away from thecoupling receptacles can be executed earlier (i.e., at the front of thesequence), the bone cuts along the cutting trajectories that arespatially closer to the coupling receptacles can be executed later(i.e., at a latter part of the sequence), and the bone cuts along thecutting trajectories that intersect with one or more couplingreceptacles can be executed last (i.e., at the end of the sequence). Theordered bone cuts as such allow the cut guide to remain securelyattached to the target bone while performing bone cuts, and prevent abone cut from interfering with the coupling between the cut guide andthe target bone. Examples of selecting guide members and generating anordered bone cut sequence are discussed below, such as with reference ofFIGS. 5A-C.

As illustrated in FIG. 4A, the navigation-based surgical system 450 canfurther include a surgical tool 455 for resecting the target boneaccording to the surgical plan such as generated by the surgicalplanning module 451. The surgical tool 455 can be adjustably positionedwithin the guide members, and can securely move along the cuttingtrajectories defined by the guide members. Examples of the surgical toocan include a surgical saw, a surgical blade, a surgical saw-blade, asurgical mill, or other surgical equipment. The surgical tool 455 can beoperated manually by an end-user such as a surgeon. Alternatively, thesurgical tool 455 can be connected to and operated by an automatedcomputer-controlled system such as a precision freehand sculptor (PFS)or other robotic surgical.

In some examples, perioperative target bone representation during thebone cuts can be updated in real-time such as using a camera and amonitoring device, or upon receiving a user command. The surgicalplanning module 451 can compute a similarity metric between the desiredbone cuts on M*_(post-op) and the perioperative bone cuts, anddetermines the bone cuts on the target bone are completed if thesimilarity metric meets a specified criterion such as falling within aspecified range or below a threshold value. The surgical plan formationmodule 453 can generate an indicator indicating the completion of thebone cut.

The communication interface 440 can be an embodiment of thecommunication interface 240, and can generate and display on a displaymodule one or more of the generic post-coupling bone model(M_(coupling)) and the target bone representations (X_(pre-coupling)),among other information as discussed with reference to FIG. 2A.Additionally, the communication interface 440 can further be configuredto generate and display on the display module one or more of the dataset representing the portion of the target bone to be altered(X_(pre-op)), the generic post-operative bone model (M_(post-op)), theselected guide members on the cut guide, the scheduled sequence of bonecuts along the cutting trajectories, the perioperative target bonerepresentation during bone cutting, and the indication of the completionof bone cuts.

FIGS. 5A-C illustrate an example of selecting a set of guide members andgenerating an ordered sequence of bone cuts along the trajectoriesassociated with the selected guide members. FIG. 5A illustrates aregistered generic post-operative bone model 510, which can be anembodiment of M*_(post-op). The model 510 has desired resection surfacerepresentations defined by flat facets 520A-D. The resection surfacerepresentations can be derived from a plurality of images ofpost-operative bones having comparable anatomical origin from a group ofsubjects. Alternatively, the resection surface representations can becomputer-simulated representations created based on the shape of thesurfaces 550A-D of the bone implant to be interfaced with the resectedtarget bone.

The orientations of the flat facets 520A-D can be compared to thecutting trajectories of the available guide members 120A-D on the cutguide 100, as illustrated in FIG. 5B. The flat facets 520A-D aredetermined to match the trajectories defined by guide members 120A-D,respectively; hence the guide members 120A-D can be selected for bonecutting. Although in this example all guide members 120A-D available inthe cut guide 100 are selected, in other examples where the cut guideincludes multiple or redundant guide members, only a subset rather thanall of the available guide members are necessarily selected to match theorientation of the desired bone cuts. In some examples, two or moreguide members having parallel trajectories can be selected, and the bonecuts can be executed along the parallel trajectories one at a time toprogressively resect the target bone in multiple layers.

An ordered bone cut sequence can be decided by comparing the locations,sizes, shapes, volumes, or other geometric or morphological descriptorsof the coupling receptacles and the cutting trajectories of the selectedguide members 120A-D. For example, the trajectories of the guide members120A and 120C shown in FIG. 5B are farther away from, and therefore lesslikely to interfere with, the coupling receptacles at the landing sites330A and 330B as illustrated in FIG. 5C. The trajectory of the guidemember 120B is close to, and is likely to interfere with, the landingsite 330A. The trajectory of the guide member 120D is close to, and islikely to interfere with, both the landing sites 330A and 330B.Therefore, bone cuts along the trajectories associated with 120A-C canbe performed first, the trajectory associated with 120B next, and thetrajectory associated with 120D the last.

FIG. 6 is a flowchart that illustrates an example of a method 600 foroperating a system to generate a cut guide positioning plan forpositioning a cut guide onto a target bone. In an embodiment, the cutguide 100 and the cut guide positioning system 200, including theirrespective various embodiments discussed in this document, can beconfigured to perform method 600, including its various embodimentsdiscussed in this document.

The method 600 can begin at 610 with receiving a representation of atarget bone, such as by using the input interface 220. The target bone,such as a portion of a femur, a tibia, or other bone or articulation inthe body, can be scheduled for surgical alteration, resection, orrepair. The target bone representation includes two or more landingsites on the target bone, such as surfaces of an acetabulum, a proximalor distal extremity of a femur, or a proximal or distal extremity of atibia. The target bone representation X_(pre-coupling) can include adata set representing the shape, appearance, contour, or other geometricor morphological characteristics of the target bone. The target bonerepresentation can also include intensity information. Therepresentation X_(pre-coupling) can include one of more of a medicalimage, a point cloud, a parametric model, or other morphologicaldescription of the target bone. Examples of medical images can includean X-ray, an ultrasound image, a computed tomography (CT) scan, amagnetic resonance (MR) image, a positron emission tomography (PET)image, a single-photon emission computed tomography (SPECT) image, or anarthrogram, among other 2D or 3D images.

At 620, a cut guide can be selected such as by a cut guide selectionmodule. The cut guide can be selected based on the size, shape, anatomy,and mechanical properties of the target bone, such that the selected cutguide can be appropriately used in assisting bone cuts on the targetbone. The selected cut guide, such as the cut guide 100, can include oneor more guide members on the body of the cut guide with pre-determinedcutting trajectories, and a plurality of landing members each includinga respective coupling feature configured to removably couple to alanding site of the target bone.

At 630, a generic post-coupling bone model (M_(coupling)) is received,such as by using the model receiver module 210. The model M_(coupling)may be derived from a plurality of images of bones taken from a group ofsubjects, where the images can have anatomical origin similar to thetarget bone representation X_(pre-coupling). The model M_(coupling) canbe in a form of a parametric model, a statistical model, a shape-basedmodel such as a statistical shape model, a volumetric model, an elasticmodel, a geometric spine model, or a finite element model. In additionto the representation of the shape and morphology of the bone, the modelM_(coupling) can include representations of two or more couplingreceptacles produced at respective two or more landing sites on thebone. An example of the coupling receptacle includes recessed portionscreated at specified landing sites on the target bone. Each couplingreceptacle is sized, shaped or otherwise configured to receive andsecure the respective coupling feature of the landing members on the cutguide. The representations of the two or more coupling receptacles caninclude indications of the location on the model M_(coupling), size,shape, volume, or other geometric or morphological descriptors. In anembodiment, the coupling receptacle representation can becomputer-simulated based on the size, shape, volume, or other geometricor morphological descriptors of the coupling features on the landingmembers of the cut guide. The computer-simulated coupling receptaclerepresentations can be added to the coupler-free normal bone model tocreate a post-coupling bone model M_(coupling).

At 640, a cut guide positioning plan for positioning the cut guide ontoor conforming to the target bone is generated, such as by using thenavigation-based guide coupling preparation system 230. To generate thecut guide positioning plan, the generic post-coupling bone modelM_(coupling) can be registered to the target bone representationX_(pre-coupling) to create a registered post-coupling modelM_(coupling). In one embodiment, the registration includes a process ofsegmentation, model transformation, and matching and alignment betweenthe target bone representation and the transformed or registered model.The bone model M_(coupling) and the target bone representationX_(pre-coupling) can each be partitioned into a plurality of segmentsrepresenting various anatomical structures on the respective image. Theportion of the M_(coupling) that contains the coupling receptaclerepresentation can be differentiated from other portions of theM_(coupling) free of coupling receptacle representation, and aregistration area free of coupling receptacle representation can beidentified from the segments of the M_(coupling). Using a comparisonbetween the coupler-free segment of M_(coupling) and the correspondingsegments of X_(pre-coupling), a desired transformation can be determinedwhich minimizes the difference between the identified couplingreceptacle-free segments on the M_(coupling) and the correspondingsegments of X_(pre-coupling). The desired transformation can then beapplied to the model M_(coupling) to create the registered post-couplingmodel M_(coupling). One or more segments of the registered post-couplingmodel M*_(coupling) can then be matched to the correspondingregistration area of the X_(pre-coupling), and the remaining segments ofthe registered post-coupling model M*_(coupling) can be aligned with theremaining segments of the target bone representation X_(pre-coupling)based on the matching.

The registered post-coupling model M*_(coupling) can then be compared tothe target bone representation X_(pre-coupling) to determine the landingsites for creating the two or more coupling receptacles, and todetermine size, shape, and other geometric or morphological descriptorsof the coupling receptacles. The landing sites of the couplingreceptacles can also be determined using information about the cutguide, including size and shape of the coupling features of the landingmembers, and the cutting trajectories associated with the guide members.

The cut guide positioning plan can be used by a system, such as the cutguide positioning system 200, for locating the landing sites on thetarget bone, and controlling a surgical cutting tool to produce two ormore coupling receptacles to desired size and shape at the landingsites. The surgical cutting tool, such as a surgical drill, a surgicalmill, a surgical saw, or other surgical equipment, can be manuallyoperated or driven by an automated computer-controlled system. The cutguide can therefore be positioned onto or conform to the target bone viathe established coupling between the coupling features on the cut guideand the coupling receptacles created on the target bone.

To ensure tight and secure coupling, the method 600 can optionallyinclude an operation of processing the interfacing surfaces of thecoupling receptacle to allow for an interference fit in at least onedimension between the coupling features and the coupling by compressionor by friction. The amount of interference can be produced at thecoupling receptacle to achieve desired tightness of fit. The positioningcan be performed manually by an operator or with the assist of anautomated system such as a computer-controlled robotic arm. Examples ofmethods for creating the coupling receptacle in accordance with the cutguide positing plan are discussed below, such as with reference of FIG.7.

In some embodiments, the method 600 can further includes providingaudio, visual, or other multi-media presentations of the post-couplingbone model M_(coupling), the registered post-coupling modelM_(coupling), the target bone representation, among other things. Thepresentation can be displayed on a monitor or other communicationinterface. The presentation formats can also include sound, dialog,text, 2D or 3D graphs, or animations to assist an end-user such as asurgeon during the process of creating and evaluating the cut guidepositioning plan. Presentation of the coupling between the target bonemodel and the cut guide, including a measurement of relative positionsbetween the coupling feature and the respective coupling receptacle, canalso be provided to the end-user when the cut guide is positioned ontoor conform to the target bone.

FIG. 7 is a flowchart that illustrates an example of a method 700 forproducing coupling receptacles on a target bone. The method 700 can beused for progressively creating bond couplers using a navigation-basedfeedback-controlled mechanism. The method 700 can be an embodiment ofproducing coupling receptacles on the target bone at 650 in method 600.

A cut guide positioning plan, including a registered post-coupling bonemodel M_(coupling), is generated at 710. The cut guide positioning planand the post-coupling bone model M*c_(oupling) can be generated usingthe steps 610-640 in the method 600. At 720, a perioperative target bonerepresentation X_(peri-coupling) can be received. The perioperativetarget bone representation X_(peri-coupling) can include a data setrepresenting the target bone with two or more coupling receptaclesduring the coupling receptacle creation process. Prior to the couplingreceptacle creating, the perioperative target bone representationX_(peri-coupling) can be initialized to the target bone representationX_(pre-coupling).

At 730, a similarity metric between the coupling receptacles on themodel M*_(coupling) and the corresponding perioperative couplingreceptacles on the representation X_(peri-coupling) is computed. In anembodiment, statistical or morphological features representing sizes,shapes, volume, or other geometric or morphological descriptors of thecoupling receptacles can be extracted from M_(coupling) andX_(peri-coupling). Similarity metric can be computed using thestatistical or morphological features of the model M_(coupling) andthose of the representation X_(peri-coupling). Examples of thesimilarity metric can include L1 norm, L2 norm (Euclidian distance),infinite norm, or other norm in the normed vector space. The similaritymetric can also include correlation coefficient, mutual information, orratio image uniformity.

The similarity metric can be provided to the operator such as a surgeonvia a displaying module, or to an automated computer-controlled system.At 740, the similarity metric can be compared to specified criterionsuch as a pre-determined threshold value. If the similarity metric failsto meet the specified criterion, the coupling receptacle creationprocess continues at 750 with further bone cut according to thepositioning plan, and peri-operative bone representation can bere-generated at 720. The navigation-based feedback-controlled couplingreceptacle creation process then continues. If, however, the similaritymetric meets the specified criterion, the perioperative couplingreceptacles on X_(peri-coupling) are deemed substantially similar to thedesired coupling receptacles on the model M_(coupling). An indicator canthen be generated to indicate a completion of the coupling receptaclecreation process at 760.

FIG. 8 is a flowchart that illustrates an example of a method 800 forresecting a portion of a target bone using a cut guide. In anembodiment, the cut guide 100 and the orthopedic surgical system 400,including their respective various embodiments discussed in thisdocument, can be configured to perform method 800, including its variousembodiments discussed in this document.

At 810, a cut guide, such as the cut guide 100, can be positioned onto atarget bone. In an embodiment, positioning the cut guide can beperformed using the method 600. A target bone representation(X_(pre-op)) is received at 820. The representation X_(pre-op) caninclude a data set representing a portion of the target bone to bealtered. For example, the representation X_(pre-op) can include amedical image, a point cloud, a parametric model, or other morphologicaldescription of the target bone. In some embodiments, the X_(pre-op) caninclude a representation of the target bone following the creation ofthe coupling receptacles.

At 830, a generic post-operative bone model (M_(post-op)) is received.The model M_(post-op) can include a data set representing apost-operative bone (i.e., after the bone cut) having an anatomicalorigin comparable to the target bone. The model M_(post-op) can be in aform of a parametric model, a statistical model, a shape-based modelsuch as a statistical shape model, or a volumetric model. In an example,the model M_(post-op) can be derived from a plurality of images ofpost-operative bones of comparable anatomical origin from a group ofsubjects. Alternatively, at least a portion of the post-operative bonemodel M_(post-op), such as the resection surfaces that interface with animplant, can be computer-simulated representation of the post-operativebone surface.

At 840, a surgical plan for altering a portion of the target bone can becreated when the cut guide is securely positioned onto or conforms tothe target bone. The post-operative bone model M_(post-op) can beregistered to the representation X_(pre-op) to create a registeredpost-operative bone model M*_(post-op). Similar to the process ofregistering the generic post-coupling bone model M_(coupling) to thetarget bone representation X_(pre-coupling) as discussed above in FIG.6, the registration can include a process of segmentation, modeltransformation, and matching and alignment between X_(pre-op) andM*_(post-op). In particular, after portioning the model M_(post-op) andthe pre-operative bone representation X_(pre-op) each into a pluralityof segments, the generic post-coupling bone model M_(post-op) can betransformed to create a registered post-operative bone modelM*_(post-op), such as using a comparison between the segment of theM_(post-op) free of resection surface representation and thecorresponding segments of the X_(pre-op). One or more segments of theregistered post-operative bone model M_(post-op) can then be matched tothe corresponding registration area of the X_(pre-op). The remainingsegments of the registered post-operative bone model M*_(post-op) can bealigned with the remaining segments of X_(pre-op) based on the matching.

A surgical plan can then be generated using the registeredpost-operative model M_(post-op) for cutting the target bone until thealtered target bone is in substantial conformity with the registeredpost-operative model M*_(post-op). The orientations of the desiredresection surface as defined by the registered post-operative modelM*_(post-op) can be compared to the cutting trajectories of the guidemembers of the cut guide. One or more guide members that match theorientation of a portion of the resection surface can then selected. Anordered sequence of bone cuts along the trajectories associated with theselected guide members is then determined. The cutting sequence can bedetermined using the anatomical, geometric, physical and mechanicalproperties of the portions of the bone to be altered. The cuttingsequence can also be scheduled considering the locations, sizes, shapes,volumes, or other geometric or morphological descriptors of the couplingreceptacles relative to the cutting trajectories. For example, the bonecuts along the cutting trajectories that are spatially farther away fromthe coupling receptacles can be executed earlier (i.e., at the front ofthe sequence), the bone cuts along the cutting trajectories that arespatially closer to the coupling receptacles can be executed later(i.e., at a latter part of the sequence), and the bone cuts along thecutting trajectories that intersect with one or more couplingreceptacles can be executed last (i.e., at the end of the sequence). Theordered bone cuts as such allow the cut guide to remain securelyattached to the target bone while performing bone cuts, and prevent abone cut from interfering with the coupling between the cut guide andthe target bone.

The target bone can then be altered at 850 in accordance with thesurgical plan. A cutting tool can be positioned in the selected guidemembers of the cut guide and resect portions of the target bone alongthe cutting trajectories in the determined ordered sequence. Bonecutting can be performed manually by an operator or with the assist ofan automated system such as a computer-controlled robotic arm. In someexamples, the method 800 can further include presenting, on a displaymodule or a communication interface, audio, visual, or other multi-mediapresentations of one or more of the data set representing the portion ofthe target bone to be altered (X_(pre-op)), the generic post-operativebone model (M_(post-op)), the selected guide members on the cut guide,and the scheduled sequence of bone cuts along the cutting trajectories,among other things.

FIG. 9 is a block diagram that illustrates an example of a machine inthe form of a computer system 900 within which instructions, for causingthe computer system to perform any one or more of the methods discussedherein, may be executed. In various embodiments, the machine can operateas a standalone device or may be connected (e.g., networked) to othermachines. In a networked deployment, the machine may operate in thecapacity of a server or a client machine in server-client networkenvironment, or as a peer machine in a peer-to-peer (or distributed)network environment. The machine may be a personal computer (PC), atablet PC, a set-top box (STB), a PDA, a cellular telephone, a webappliance, a network router, switch or bridge, or any machine capable ofexecuting instructions (sequential or otherwise) that specify actions tobe taken by that machine. Further, while only a single machine isillustrated, the term “machine” shall also be taken to include anycollection of machines that individually or jointly execute a set (ormultiple sets) of instructions to perform any one or more of themethodologies discussed herein.

The example computer system 900 includes a processor 902 (such as acentral processing unit (CPU), a graphics processing unit (GPU), orboth), a main memory 904 and a static memory 906, which communicate witheach other via a bus 908. The computer system 900 may further include avideo display unit 910 (such as a liquid crystal display (LCD) or acathode ray tube (CRT)), an alpha-numeric input device 912 (such as akeyboard), a user interface (UI) navigation device (or cursor controldevice) 914 (such as a mouse), a disk drive unit 916, a signalgeneration device 918 (e.g., a speaker) and a network interface device920.

The disk drive unit 916 includes a machine-readable storage medium 922on which is stored one or more sets of instructions and data structures(e.g., software) 924 embodying or used by any one or more of the methodsor functions described herein. The instructions 924 may also reside,completely or at least partially, within the main memory 904, staticmemory 906, and/or within the processor 902 during execution thereof bythe computer system 900, the main memory 904 and the processor 902 alsoconstituting machine-readable media. In an example, the instructions 924stored in the machine-readable storage medium 922 include instructionscausing the computer system 900 to receive receive a target bonerepresentation including a data set representing two or more landingsites of the target bone (X_(pre-coupling)), to select a cut guideconfigured to be adjustably positionable onto or otherwise to conform tothe target bone, and to receive a generic post-coupling bone model(M_(coupling)) including a data set representing a bone having the twoor more coupling receptacles. The instructions 924 can also store theinstructions 924 that cause the computer system 900 to generate a cutguide positioning plan for positioning the cut guide onto or conformingto the target bone.

The machine-readable storage medium 922 may further store theinstructions 924 that cause the computer system 900 to produce,respectively at the two or more landing sites, the two or more couplingreceptacles sized, shaped or otherwise configured to receive and securethe respective coupling feature of each of the plurality of landingmembers, and to attach the cut guide to the landing site of the targetbone by respectively engaging the coupling features with the couplingreceptacles. The instructions in the machine-readable storage medium 922may also cause the computer system 900 to receive a target bonerepresentation including a data set representing a portion of the targetbone to be altered, receive a generic post-operative bone modelincluding a data set representing a post-operative bone having ananatomical origin comparable to the target bone, generate a surgicalplan for altering a portion of the target bone when the cut guide issecurely positioned onto or otherwise conforms to the target bone, andalter the target bone in accordance with the surgical plan using thecutting tool and the cut guide.

While the machine-readable medium 922 is shown in an example embodimentto be a single medium, the term “machine-readable medium” may include asingle medium or multiple media (e.g., a centralized or distributeddatabase, and/or associated caches and servers) that store the one ormore instructions or data structures. The term “machine-readable storagemedium” shall also be taken to include any tangible medium that iscapable of storing, encoding or carrying instructions for execution bythe machine and that cause the machine to perform any one or more of themethods of the present invention, or that is capable of storing,encoding or carrying data structures used by or associated with suchinstructions. The term “machine-readable storage medium” shallaccordingly be taken to include, but not be limited to, solid-statememories, and optical and magnetic media. Specific examples ofmachine-readable media include non-volatile memory, including by way ofexample, semiconductor memory devices (e.g., erasable programmableread-only memory (EPROM), electrically erasable programmable read-onlymemory (EEPROM)) and flash memory devices; magnetic disks such asinternal hard disks and removable disks; magneto-optical disks; andCD-ROM and DVD-ROM disks. A “machine-readable storage medium” shall alsoinclude devices that may be interpreted as transitory, such as registermemory, processor cache, and RAM, among others. The definitions providedherein of machine-readable medium and machine-readable storage mediumare applicable even if the machine-readable medium is furthercharacterized as being “non-transitory.” For example, any addition of“non-transitory,” such as non-transitory machine-readable storagemedium, is intended to continue to encompass register memory, processorcache and RAM, among other memory devices.

In various examples, the instructions 924 may further be transmitted orreceived over a communications network 926 using a transmission medium.The instructions 924 may be transmitted using the network interfacedevice 920 and any one of a number of well-known transfer protocols(e.g., HTTP). Examples of communication networks include a LAN, a WAN,the Internet, mobile telephone networks, plain old telephone (POTS)networks, and wireless data networks (e.g., Wi-Fi and WiMAX networks).The term “transmission medium” shall be taken to include any intangiblemedium that is capable of storing, encoding or carrying instructions forexecution by the machine, and includes digital or analog communicationssignals or other intangible media to facilitate communication of suchsoftware.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, in an example, the code can be tangiblystored on one or more volatile, non-transitory, or non-volatile tangiblecomputer-readable media, such as during execution or at other times.Examples of these tangible computer-readable media can include, but arenot limited to, hard disks, removable magnetic disks, removable opticaldisks (e.g., compact disks and digital video disks), magnetic cassettes,memory cards or sticks, random access memories (RAMs), read onlymemories (ROMs), and the like.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A system for use in orthopedic surgery on a bone,the system comprising: a cut guide to be positioned onto the bone, thecut guide comprising a guide body configured to be coupled to the boneto provide a secure attachment of the cut guide to the bone duringperformance of at least one bone cut, the guide body having a bonefacing surface to be positioned onto the bone and at least one guidemember configured to guide a cutting tool along a planned planar cuttingtrajectory, wherein the cut guide comprises a plurality of landingmembers, each of the plurality of landing members being a structureseparate from the guide body and fixable onto the bone facing surface ofthe guide body so as to couple the guide body onto the bone, and whereinthe plurality of landing members are configured to position the cutguide onto the bone such that the at least one guide member isconfigured to guide the cutting tool along the planned planar cuttingtrajectory; a processing device including cut guide positioning planninginstructions stored therein to generate a cut guide positioning plan,wherein the cut guide positioning plan is generated at least in partusing a bone model, wherein the bone model includes a data setrepresenting a bone having an anatomical origin comparable to the boneto be altered by the system; a computer-controlled robotic armconfigured to assist an operator in positioning the cut guide onto thebone based on the cut guide positioning plan; and a communicationinterface configured to display a real time perioperative target bonerepresentation to assist the operator during positioning of the cutguide onto the bone and to display the planned planar cutting trajectoryof the bone prior to execution of the planar cut.
 2. The system of claim1, further comprising a coupling receptacle preparation tool configuredto be operated manually by the operator to create a plurality ofreceptacles on the bone.
 3. The system of claim 2, wherein each of theplurality of receptacles has a size and shape based on a structure of arespective one of the plurality of landing members.
 4. The system ofclaim 1, wherein the processing device further includes a surgicalplanning module configured to generate a surgical plan for altering atleast a portion of the bone when the cut guide is positioned onto thebone.
 5. The system of claim 4, further comprising the cutting toolconfigured to be positioned within the at least one guide member forresecting the bone based on the surgical plan.
 6. The system of claim 1,wherein the guide body is configured to be adjustably coupled to thebone using pins.
 7. The system of claim 1, wherein the bone model is oneof a parametric model, a statistical model, or a statistical shapemodel.
 8. The system of claim 1, wherein the bone model is generatedusing two-dimensional image data of the bone.
 9. The system of claim 1,wherein the bone is a femur.
 10. The system of claim 9, wherein theplanned planar cutting trajectory corresponds to the distal femur cut ina total knee arthroplasty procedure.
 11. The system of claim 1, whereinthe bone is a tibia.
 12. The system of claim 1, wherein the cut guidepositioning plan can be modified intraoperatively.